Illumination devices and methods of forming same

ABSTRACT

Illumination devices and methods of forming illumination devices, utilizing optical light films are disclosed. Joints useful in forming light carriers from optical light films are also disclosed.

This application is a continuation in part of U.S. patent applicationSer. No. 08/055,188 filed on Apr. 30, 1993, now U.S. Pat. No. 5,475,785,and U.S. patent application Ser. No. 08/077,415 filed Jun. 15, 1993, nowU.S. Pat. No. 5,483,119.

BACKGROUND OF THE INVENTION

The present invention relates to light conducting and light emittingtubes, herein referred to as "light tubes", and novel optical lightfilms having an embossed prism pattern to contain and channel the lightwhen formed into a tube. More particularly, the present invention isconcerned with laminated tube construction and methods of constructinglight tubes to achieve a wide range of illumination effects includingthe piping of light from an accessible, concentrated light source todistal areas and the release of such light in widely variable patterns.

Optical light films (OLFs) can be efficiently manufactured from polymersin flat, flexible, but fragile films and made to perform a myriad ofillumination functions. The film can be formed into various tubular andother partially closed configurations by supporting it together withsupplemental light controlling films or elements in preformed carriertubing having light-permeable characteristics. For example, a sheet ofOLF can be formed into a closed tube by disposing one longitudinal edgeof the OLF adjacent the opposite longitudinal edge. Alternatively, asheet of OLF can also be formed into a partially closed tube, forexample having an arched cross-section, and maintained in such aconfiguration with a supporting structure. As used herein, the term"tube" is meant to include both closed and partially closedconfigurations.

In addition to carrying light from a source of illumination such as ahigh-intensity light bulb to a remote location, light tubes can also beused for emitting light over relatively large areas. For this purpose,various methods have been devised to direct light out of a light tubeover portions of the tube length. One method involves placing a clearadhesive tape on the outer, grooved side of an optical light film. Aclear tape placed in this manner reduces the internal reflectance of theoptical light film in the taped area and essentially creates a windowfor "escaping" light. Another method simply involves removing a sectionof the optical light film where internal reflectance is not desired.Portions of a tube lacking optical light film will permit light toescape. A third method comprises forming a light tube with some meansfor directing the light at the walls of the optical light film at anangle greater than about 28°. At such angles of incidence, the internalreflectance of the optical light film is greatly reduced. For example,the 3M Company of St. Paul, Minn., produces a product marketed under thename "2370" which directs incident light at an angle of about 90° to theangle of incidence. If a piece of "2370" is positioned within a lighttube, light moving generally along the longitudinal axis of the tubewill be directed through the "2370" substantially perpendicular toward asidewall and out of the light tube. Another product, marketed under thename "SCOTCH-CAL EXTRACTOR FILM™", directs light toward and through anopposite interior wall.

Since optical light film is fragile and sensitive to dirt and moisture,it is typically positioned within protective, outer tubes. Such tubesare generally transparent and can have a variety of finishes, e.g.clear, matte, colored or opaque. The ability to insert the fragileoptical light films into a carrier tubing, typically an extrusionproduct, is an impediment to the light tube designer. Moreover, shippingfabricated light tubes is costly because of their high volume relativeto volume of component displacement and their inherent vulnerability todamage by breaking and scratching. Thus the low manufacturing cost ofthe critical optical film component is heavily offset by shipping costs.Also lost is the ability of the designer to achieve at acceptable costfinished products which feature many of the useful and underlyinglighting functions which the optical light film is inherently capable ofperforming.

It would therefore be desirable to provide novel methods for forminglight tubes and light tube products using the films which are costeffective, optically efficient and functionally varied.

SUMMARY OF THE INVENTION

The present invention comprises improvements in methods of forming lightcarriers and the resulting light carriers comprising optical light film.

One embodiment of the present invention comprises an optical light filmformed with a generally U-shaped connector which, along with otherelements, forms slots for securely receiving at least portions of thelongitudinal edges of the optical light film. This embodimentadvantageously permits on-site fabrication of light tube havingsubstantially total (i.e. 360°) internal reflectance.

Another embodiment of the present invention comprises an improvedoptical light film which advantageously allows controlled amounts oflight to exit the light tube without the need for supplementalextractors.

Another embodiment of e present invention comprises a decorative lightfixture comprising a source of illumination, a light tube comprising OLFwhich emits light over the length of the tube and is also provided withan emitter for changing the direction of light exiting the distal end ofthe light tube.

A still further embodiment of the present invention comprises adecorative illumination device comprising a light tube disposedsubstantially concentrically within an outer protective tube.

A further aspect of the present invention comprises a novel, heatresistant connector which provides a durable connection between lighttubes or portions of light tubes, for example between a optical lightfilm tube and a bulb housing.

Another aspect of the present invention comprises a light tubecomprising a tapering, optical light film tube. As explained in greaterdetail below, a substantially continuous illumination may be obtainedover the length of a light tube by providing a carefully measuredconverging taper to the light tube in the direction extending away fromthe source of illumination.

Another decorative embodiment of the present invention comprises twosheets of optical light film positioned with the grooves in contact andwith the grooves disposed at an angle of at least 45°, and mostpreferably at an angle of substantially 90°. This embodiment creates thedecorative illusion of a flame in the light tube. Colored filters can beused to provide images of flames of different colors.

Another embodiment of the present invention comprises a first sheet ofoptical light film connected to an outer, protective sheet of a secondmaterial in an area remote from the edges of the two sheets. Theopposing longitudinal edges of both sheets are configured such that thesecond edge of the optical light film is positioned between the firstedge of optical light film and the first edge of the outer protectivesheet while the second edge of the outer protective sheet is connectedwith a first edge region of the protective sheet. This light tubeprovides a sheet of optical light film substantially surrounded by anouter, protective sheet which facilitates maintaining the optical lightfilm in a clean, dry and optically efficient condition.

Another aspect of the present invention comprises connecting two sheetsin a manner similar to that described above and disposing at least onesheet of optical light film between the two sheets.

These and other embodiments are described in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a light tube and bulb of one embodimentof the present invention.

FIG. 2 is a cross-sectional view of a connector used with the light tubeillustrated in FIG. 1.

FIGS. 3-5 are cross-sectional views illustrating the arrangement offilms and a connector of two embodiments of the present invention.

FIG. 6 is a cross-sectional view of an illumination device of thepresent invention.

FIGS. 7-12 illustrate various emitters which may be used with theillumination device illustrated in FIG. 6.

FIGS. 13 and 14 illustrate an optical light film of the presentinvention.

FIGS. 15 and 16 illustrate the arrangement of a plurality of opticallight films used in another embodiment of the present invention.

FIGS. 17 and 18 illustrate the effects of using a tapering light tube ofanother embodiment of the present invention.

FIG. 19 illustrates an illumination device of another embodiment of thepresent invention which utilizes at least one tapering light tube.

FIG. 20 illustrates a tube-in-a-tube embodiment of the presentinvention.

FIGS. 21-28 illustrate methods of the present invention for disposing alight tube within a preformed carrier.

FIG. 29 illustrates a plunger which is useful with the methodsillustrated in FIGS. 21-28.

FIGS. 30 and 31 are cross-sectional views of one embodiment of a lighttube of the present invention.

FIGS. 32 and 33 are cross-sectional views illustrating anotherembodiment an optical light tube of the present invention.

FIGS. 34 and 35 illustrate a terminal, overlapping joint of oneembodiment of the present invention.

FIG. 36 illustrates a connector ring of another embodiment of thepresent invention.

FIG. 37 illustrates a still further connector ring of another embodimentof the present invention.

FIGS. 38 and 39 are partial, cross-sectional views of a light carrier ofan alternative embodiment of the present invention.

DETAILED DESCRIPTION

One embodiment of the present invention is directed to a light carriercomprising at least one sheet of optical light film 10 which ismaintained in a tube configuration by a novel joint. The optical lightfilm preferably has enough flexibility and sufficient width so that onelongitudinal edge 14 can be moved to a position proximate the otherlongitudinal edge 14 thereby forming a tube, preferably having agenerally cylindrical shape. Unless otherwise specified, the term"optical light film" is used herein to refer to flexible films having asurface comprising a plurality of substantially triangular grooves whichreflect substantially all of the light incident on the opposite side ofthe film at an angle of less than about 28° when formed into a lighttube. Such film is available from the 3M Corporation, St. Paul, Minn.

According to this embodiment of the present invention, which isillustrated in FIGS. 1-5, the opposing longitudinal edge regions of anoptical light film 10 are maintained in position using a generallyU-shaped connector 20 proximate bulb 11. With reference to FIG. 2 whichillustrates one particularly preferred embodiment of a U-shapedconnector 20, comprising a pliable strip 21 provided with a first stripof adhesive tape 22 on the top of one end of the flexible strip and asecond strip of adhesive tape 24 positioned on the bottom of the otherlongitudinal edge of strip 21. The strip 21, which is preferably formedof a clear polymeric material, is then simply configured to form thegenerally U-shaped connector 20 illustrated in FIG. 2. As illustrated,according to this embodiment, the upper side of the U-shaped connector20 is preferably longer than the bottom side and the first adhesive tape22 affixed to the upper side does not extend to the point on the strip20 where the strip 20 is folded. As shown, once the flexible strip isfolded into the U-shape, the second adhesive tape 24 is on the innersurface of the U-shaped member and the first adhesive 22 is on anoutside surface of the U-shaped member.

As illustrated, it is not necessary that both sides of the U-shapedmember have the same length. It will also be noted that the adhesivetape may be a double-sided adhesive tape, i.e., a central carrier havingadhesive on both sides. More preferably, the adhesive tape can be a VeryHigh Bond Tape available from the 3M Corporation of St. Paul, Minn.which exhibits adhesiveness throughout. Those skilled in the art willalso appreciate that the thickness of the adhesive tape utilized can bevaried for different applications depending upon such factors as thestrength required and any thickness characteristics inherent in theparticular tube design.

According to the illustrated embodiment, a second flexible sheet 30substantially surrounds and protects the optical light film 10. Informing this embodiment, at least a portion of longitudinal edge 12 ofthe optical light film 10 is inserted into the slot defined by thesecond adhesive tape 24 and the inner surface of the U-shaped connector20. With reference to FIG. 3, a contact region 32 which is remote from alongitudinal edge of the second sheet 30 is then contacted with thefirst adhesive tape 22. The longitudinal edge region 34 of the secondsheet 30, along with the exposed, upper, outer surface 26 of theU-shaped member, forms a slot for receiving the other end of the opticallight film 10. Prior to configuring the optical light film 10 to formthe substantially closed light tube, another strip of adhesive tape 36is preferably positioned on the bottom surface the opposing edge of thesecond sheet 30 proximate opposing edge 38. In this manner, when thesheets are configured to place the edge of the optical light film 10into the slot defined by the U-shaped member 20 and the first edgeregion 34 of the second sheet 30, the second edge region 38 of thesecond sheet 30 can be readily adhered to the top of the first edgeregion 34 of the second sheet 30 in the manner illustrated in FIG. 4.This embodiment is particularly useful in forming tubes withpredetermined diameter(s) over the length of the tube. Additionally,this embodiment advantageously permits on-site fabrication of light tubehaving substantially total (i.e. 360°) internal reflectance.

Depending upon the intended use of the light tube, it may be desirableto sandwich one or more sheets of optical light film between sheets ofpolymeric material. According to an alternative embodiment of thepresent invention illustrated in FIG. 5, this can be readilyaccomplished in a fashion similar to the embodiment illustrated in FIGS.2-4 by positioning a sheet of optical light film 40 on the exterior sideof a third sheet 41 which is preferably at least approximately the samesize as the optical light film 40 and then inserting the third sheet 41into the slots defined above. Namely, one longitudinal edge of sheet 41is advantageously inserted into a first slot defined by an inside wallof the U-shaped connector 46 and an adhesive 42, and the oppositelongitudinal edge is placed into a second slot defined by an outsidesurface 43 of the U-shaped member 46 and an edge region 44 of theoutermost sheet 45. From the present description, those skilled in theart will appreciate that the upper longitudinal edge regions, as shownin FIGS. 2-5, will be held within the second slot in part, due to anedge bond with the adhesive tape 47 positioned on the upper, outersurface 43 of the U-shaped member 46. This edge bond provides additionaladherence but is not necessary in order to practice this embodiment ofthe present invention.

Another embodiment of the present invention utilizes the decorativeadvantages of a light tube in a novel light fixture. In accordance withthe illustrated embodiment shown in FIG. 6, this light fixture comprisesa light source, preferably comprising a metal halide bulb 51, a ballast52, a decorative light tube 60 and a light emitter 75. While theillustrated embodiment shows a metal halide bulb it is also within thescope of the present invention to use other types of bulbs, such assulphur bulbs.

According to the illustrated embodiment which is in the form of ahanging light fixture, a support hanger 50 is suitably wired to a supplyof electrical power and to ballast 52 which in turn powers bulb 51.According to the illustrated embodiment, bulb 51 is preferablypositioned within a protective housing.

As shown in FIG. 6, the illustrated housing comprises outer sleeve 55and an inner sleeve 56. Outer sleeve 55 is removably connected to a topcover 54 by a twist connector 57. Outer sleeve 55 can therefore bereadily removed by simply rotating outer sleeve 55 relative to top cover54. Inner sleeve 56 is advantageously provided with sufficient openingsto allow a person to change bulb 50 after outer sleeve 55 has beenremoved. Outer sleeve 55 can then be raised back into position andsecured to upper support 54.

As shown in FIG. 6, light tube 60 is suspended from inner sleeve 56.While those skilled in the art will appreciate that there are manysuitable methods of connecting light tube 60 to inner wall 56, theillustrated embodiment utilizes a mechanical connection comprisingscrews 57 which pass through holes in clips 110 light tube 60. Clips 110are suspended from flanges 112 which are connected, for example bywelding, to inner wall 56. Clips 110 extended downwardly beyondretaining ring 70 and preferably overlap a portion of light tube 60. Inorder to provide greater support and reduce the likelihood of damage tothe light tube 60, a substantially rigid support ring 58 isadvantageously positioned inside the upper portion of light tube 60. Thesubstantially rigid ring may be formed of any suitable material, forexample, a metal such as polished aluminum. The illustrated embodimentalso comprises a spacer 59 in order to maintain the light tube 60 andinner protective wall 56 in a substantially-parallel spaced relation.Therefore, supporting screws 57 pass through holes in rigid support ring58, light tube 60, spacer 59 and clips 110. Screws 57 do not contactouter protective sleeve 55 and therefore do not interfere with themovement of outer sleeve 55 when it is necessary to change a light bulb51. In this manner, vertical support is provided to light tube 60 andlight tube 60 is also substantially thermally insulated from the heat ofbulb 51.

In order to obtain desired lighting effects, it may be desirable toposition lenses, for example colored lenses, or light filters betweenbulb 51 and light tube 60. For this purpose, a retaining ring 70 isadvantageously disposed below bulb 51. In the illustrated embodiment, alens 53 is maintained in a position substantially perpendicular to thelongitudinal axis of the light tube with a retaining ring 70 formed of aheat resistant material. For example, the retaining ring 70 may beformed of a silicone compound, such as "6750 or 6770 silicon resin" soldby General Electric Company of Waterford, N.Y., which is sufficientlypliable to allow the retaining ring 70 to be positioned within the bulbhousing and also to permit the placement of lenses. The illustratedretaining ring 70 is provided with two inwardly facing grooves 71 andtwo vertically disposed grooves 72, one opening upwardly and the otheropening downwardly.

As illustrated in FIG. 6, light tube 60 of the illustrated embodimentadvantageously extends upwardly beyond the upper edge of rigid ring 58into the lower slot 72 of lens retaining ring 70. A suitableheat-resistant adhesive may also be used within lower vertical groove 72for bonding retaining ring 70 onto light tube 60. The mechanicalconnection performed by screws 57 provides support to retaining ring 70.Retaining ring 70 may also be used to support a clear tempered glasslens. Tempered glass is particularly advantageous since it prevents someof the ultraviolet waves and heat emitted by a light source from harmingthe polymers used in this illumination device. It also keeps out dustand moisture. Retaining ring 70 may also be used to support a coloredfilter 114 in order to create desired illumination effect.

While those skilled in the art will appreciate that variations in theconstruction of the illustrated light tube 60 may be made withoutdeparting from the scope of the present invention, for purposes ofillustration, the light tube shown in FIG. 6 is shown as simplycomprising an inner sheet of optical light film 61 and an outer sheet 66of a protective polymeric material. From the present description anddrawings, those skilled in the art will also appreciate that a widevariety of designs may be employed in the construction of light tube 60.The amount of light exiting through the side walls of the light tube canbe varied through the use of extractors described above and/orinterruptions in the optical light film. FIG. 6 illustrates an extractor118 formed into the shape of a star and a relieved section 119 whereinthe optical light film has been removed in order to interrupt theinternal reflectance in these areas.

The direction of light exiting the bottom of the light tube may becontrolled by a light emitter. Light emitter may be of a wide variety ofdesigns depending on the desired illumination. The emitter, which isshown in greater detail in FIG. 7, comprises an outlet cap 75 formed ofa heat resistant material, such as a silicone compound. Outlet cap 75preferably comprises at least an upper-inwardly facing slot 76 and alower inwardly-facing slot 77 in the same manner as retaining ring 70.Upper slot 76 is preferably utilized to support a protective,transparent bottom cover 78 which may be formed of any suitable,heat-resistant material such as a transparent tempered glass. Bottomcover 78 serves to prevent dust, other dirt and moisture from enteringthe interior of the light tube. Lower slot 77 supports a light emitter74 which comprises four glass disks positioned substantiallyperpendicular longitudinal axis of the light tube.

Another light emitter 80 is illustrated in FIGS. 8 and 9. Light emitter80 comprises a plurality of reflectors 81 pivotally supported on hinge83 in a manner which permits reflectors 81 to be positioned at variousangles relative to the longitudinal axis of the tube. According to thisembodiment, the user of the light carrier is provided with the option ofreflecting substantially all incident light back into the light tube orpositioning one of the reflectors at an angle to direct the light out ofthe egress end of the tube at an angle to the longitudinal axis of thelight tube.

In the emitter illustrated in FIG. 10, a reflective ring is disposed inthe lower slot of outlet cap 75 in order to reflect the portion of thelight closest to the walls of light tube 60 back into the light tube.The outer portion 84 of the reflective ring is reflective while theinner portion 85 is transparent.

An alternative embodiment is illustrated in FIG. 11 wherein the lowerslot 77 of outlet cap 75 supports a disk having an outer transparentportion 86 and an inner reflective portion 87. This embodiment of thepresent invention reflects the portion of light near the centrallongitudinal axis of the light tube back into the tube while allowing anouter ring of light to be emitted.

According to a still further embodiment of the present inventionillustrated in FIG. 12, a right angle turning lens 88, may be positionedat an angle of 45° to the longitudinal axis of light tube 60 in order todirect the light at an angle substantially perpendicular to the centrallongitudinal axis of the tube. Those skilled in the art will appreciatethat other lenses could be used for directing light at different angles.

Those skilled in the art will also appreciate that the decorativeaspects of the light tubes illustrated in FIGS. 6-12 can be variedthrough the use of colored filters or colored protective polymeric filmsor tubes.

Another preferred aspect of these embodiments of the present inventioncomprise some manner of extracting light out of these illuminationsdevices in the region of the optical light film. For example, one of theextractors described above may be utilized. A section of the OLF canalso be cut away to provide a relieved section 119, preferably in theform of some decorative shape. From the present description, it will beappreciated that by removing a portion of the optical light film, theinternal reflectance at such portions of the illumination device iseliminated. Various shapes and letters can be cut from the optical lightfilm or an extractor 89 can be employed in the manners illustrated inFIG. 6.

Another aspect of the present invention comprises a light tube formedwith an improved optical light film. According to this embodiment of thepresent invention which is illustrated in FIGS. 13-15, some of the peakson the grooved side of an optical light film are modified in order toreduce the internal reflectance of those areas of the optical lightfilm. Those skilled in the art will appreciate that the internalreflectance property of optical light film is dependent upon preciselyformed ridges on the outside surface of a light tube. These ridges aretypically formed with sidewalls converging at angles of about 90°. If,however, these ridges are modified by removing a portion of the peak,light incident on the modified portion will have a much greater tendencyto "escape" from the light tube than in a conventional light tube. Thisembodiment of the present invention advantageously eliminates the needfor supplemental extractors which are used to reduce the internalreflectance of a portion of the optical light film.

With reference to FIG. 13, conventional peak 210 is defined byconverging sidewalls 211 which meet at an angle of about 90° forming asubstantially triangular cross section. Typically, light incident uponone side wall 211 of a tube at an angle of incident less than about 28°will be reflected to the adjacent sidewall of the same peak and thenreflected internally back into the interior of the light tube. In theillustrated embodiment, light incident on a modified portion 215 willescape while light incident on an unmodified portion 216 of a modifiedpeak will still be internally reflected.

The peaks of the light film can be modified after manufacturing in anysuitable manner. For example, the ridges may be precisely milled,scraped, melted, e.g. with a laser beam, or if less precision isrequired, crushed between rigid rollers. Those skilled in the art willappreciate that the amount of light escaping through a modified peakwill be dependent upon the amount of the peak that has been modified. Asshown in FIG. 14, a single ridge can have different degrees ofmodification in order to permit a greater amount of incident light toexit at one end of the tube. Those skilled in the art will appreciatethat a greater amount of light will typically pass through the tube(escape) at the end closer to the source of illumination. Therefore, bymodifying a greater portion of the ridge at the distal end which isfurther away from the light source, a substantially constant amount oflight can be emitted over the entire length of the tube.

In addition to providing the method of modifying optical light filmdescribed above, the present invention also includes an optical lightfilm which is initially formed without perfect peaks in desired areas inorder to allow the escape of light in those regions.

Another embodiment of the present invention provides a decorative lightcarrier which creates an apparently changing illumination, generally inthe shape of a flame, as the distance between the observer and thedevice changes. This embodiment, which is illustrated in FIGS. 15-16, isformed by placing two sheets of optical light film into contact, withthe ridged sides touching and with the ridges positioned at an angle ofat least 45°, preferably at least 70° and most preferably substantiallyperpendicular. This decorative light tube is most preferably arrangedsuch that the ridges of the inner optical light film are arranged in thesame direction as the longitudinal axis of the tube. According to thepreferred illustrated embodiment shown in FIG. 16, two sheets of opticallight film are disposed within a protective outer transparent film 220.The ridges of the inner optical film 230 are preferably positionedsubstantially parallel to longitudinal axis L while the ridges of theouter optical light film 240 extend circumferentially around the tube.

Another embodiment of the present invention provides a light tube havinga diameter which decreases toward the distal end 270 of the light tube,i.e., in the direction away from the source of illumination 271. Sincethe amount of light escaping from a tube is directly proportional to theamount of light striking the sidewalls of the tube, at angles less thanthe critical angle of reflectance which is about 28°, greater quantitiesof light can be emitted from the distal end by decreasing the diameterof the tube and thereby increasing the incidence of light on the smallend of the tube. FIGS. 17 and 18 illustrate this principle wherein alight ray emanating from a light source impinges upon the sidewall oftwo light tubes, one having a constant diameter and the other tapered.As generally illustrated, the taper will increase the frequency ofcontacts between a light beam and the sidewalls of a light tube. Thisembodiment is preferably constructed by cutting a sheet of optical lightfilm into a trapezoidal shape, shaping the optical light film into atapered tube, and securing the ends of the tapered light tube. Thelength of the tube and the degree of taper are limited only by thestarting materials. For example, one such tapered tube has an ingressend with a diameter of about eight inches which tapers down to an egressdiameter of about four inches over a longitudinal length of about 4feet.

From the present description, it will be appreciated that rings, such asthe heat resistant retaining rings described above, will have many usesin illumination devices. Rings constructed in the fashion illustrated inFIGS. 6-12 may also be utilized to form other useful illuminationdevices. For example, FIG. 19 illustrates another use of a taperinglight tube 393 and heat-resistant rings 392, 394. In this embodiment ofthe present invention, a light source 390 is positioned within a lighthousing 391. The light housing 391, which has a first diameter, isconnected to a tapering light tube 393 with a ring 392. Ring 392 ispreferably of the type illustrated above in FIGS. 6-12. A second ring394 having a different diameter is utilized to connect the other end oftapering tube 393 to another light tube which has a diameter orcross-sectional configuration which is different from that of lighthousing 391. This embodiment of the present invention is particularlysuited for connecting elements that have cross-sections of differentsizes and/or shapes.

FIG. 20 illustrates a still further use for the illustrated ringswherein a tube-in-a-tube construction is formed using an inner retainingring 310 which is positioned inside an outer retaining ring 320 having alarger diameter. In the manner illustrated in FIG. 20 the innerretaining ring 310 is positioned by a spacer ring 315 which is held inplace by an inwardly facing groove of outer retaining ring 320. Thespacer ring 315 can be formed of any substantially rigid material, forexample a metal or a plastic. The spacer ring 315 is most preferablyheat resistant. This tube-in-a-tube construction is particularly usefulfor providing a protective casing 340 for a light tube 330 and/orproviding a colored or finished cover to create a desired light effect.Casing 340 can advantageously comprise a plurality of layers.

Another aspect of the present invention comprises methods of forminglight tubes within pre-formed carriers, for example polycarbonate tubes.From the description below, those skilled in the art will appreciatethat the methods described herein may also be utilized to form lighttubes in carriers that are not circular in cross-section as well ascarriers that are not completely continuous, i.e. closed incross-section. One method of forming light tubes within a cylindricalcarrier is illustrated in FIGS. 21-28. These methods are particularlyuseful in forming light tubes within pre-formed cylindrical tubes. Forexample, light tubes having a diameter of 4 inches can be readily formedin lengths of 20 feet.

With reference to FIG. 21, the first step comprises providing a gutter410 preferably having a length equal to the length of the final lighttube and a longitudinal relieved section defined by opposing side wallsof gutter 410 through which an optical light film can be inserted. Fromthe description above, it will be appreciated that in order to conductlight, optical light films used with the various embodiments of thepresent invention have a plurality of prismatic grooves/peaks which faceoutwardly when the optical light film is formed into a light tube. Inorder to prevent these peaks/grooves from being damaged along the edgesof gutter 410, a protective sheet 430 is advantageously placed betweenthe optical light film and the gutter 410. The protective sheet 430 ispreferably formed of a material which has is pliable and has asubstantially low coefficient of friction with the other elementsutilized during this assembly procedure. For example, when the gutter410 is formed of a polycarbonate, protective sheet 430 may be formed ofa material such as Tyvek™ sold by DuPont of Wilmington, Del.

With the protective sheet 430 in place, the optical light film 420 canthen be pushed into gutter 410 with the help of a weighted rod 440 inthe manner shown in FIG. 22. The heavy rod 440 is then removed and theoptical light film 420 and protective sheet 430 can be adjusted inwardlyto correspond with the general shape of gutter 410 in the manner shownin FIG. 23. The lower edge 431 of protective sheet 430 is then foldedunder the upper edge 432 in the manner illustrated in FIG. 24 and thenthe upper edge 432 is also folded inwardly such that the entire opticallight film 420 and protective sheet 430 are disposed within gutter 410in the manner shown in FIG. 25. Since gutter 410 has a diameter lessthan the diameter of the tube 450 into which the optical light film willbe ultimately disposed, gutter 410 is then simply inserted into an openend of tube 450.

According to this embodiment of the present invention, the optical lightfilm 420 is then attached, e.g. clamped, to the end of outer tube 450and the gutter 410 and protective sheet 430 are removed from the otherend, leaving optical light film 420 within outer tube 450 in the mannershown in FIG. 27. If the optical light film, due to its inherentresiliency and elasticity, does not conform to the inner surface ofouter tube 450, a plunger 460, for example having a cross-section suchas the one shown in FIG. 29, can be pushed into the interior of opticallight film 420 forcing the optical light film 420 outwardly such thatthe opposing edges of optical light film 420 snap into position as shownin FIG. 28.

According to another embodiment of the present invention which providesan alternative method for installing an optical light film into a closedrigid tube, the steps illustrated in FIGS. 21-25 are repeated. Thelongitudinal recess of the gutter 410 may optionally be blocked toprevent the optical light film 420 and protective sheet 430 from workingtheir way out of gutter 410. In this embodiment, one end of gutter 410is then aligned with an open end of outer tube 450, a flexible lead isfed through outer tube 450 and attached to protective sheet 430 andoptical light film 420. The protective sheet 430 and optical light film420 are then drawn out the open end of gutter 410, which is maintainedsubstantially outside of outer tube 450, and into outer tube 450.

The protective sheet 430 is preferably a flexible material having a lowcoefficient of friction and is substantially tear-resistant such that itwill not tear upon contact with the edges of the gutter 410. While anylow friction, tear-resistant material can be utilized, the materialwhich has been found useful is Tyvek™ made by Dupont, of Wilmington,Del.

The protective sheet 430 can then be readily removed in the mannerdescribed above by clamping one end of the optical light film 420 to theouter tube 450 and drawing the protective carrier 430 out the other end.If the optical film 420 did not conform to the inner surface of tube450, for example as shown in FIG. 27, the plunger 460 illustrated inFIG. 29 can again be utilized in the manner described above.

Unlike methods heretofore described and utilized in the art, the methodsof the present invention provide for ways of positioning optical lightfilm within rigid tubes with a minimal amount of manpower. Previousmethods which required the rolling of a sheet of optical light filmwithin an outer protective, lowfriction sheet required numerous pairs ofhands, and were therefore cost-intensive. Another disadvantage of suchmethods was that the rolled-up optical light film and protective sheetwould tend to unroll and would become very difficult to push into theouter tube. Another disadvantage is that the fragile optical light filmcannot withstand too much pushing before fracturing. The methods of thepresent invention advantageously minimize the amount of stress placed onthe fragile optical light film.

Another aspect of the present invention comprises a method of disposingan extractor in a light tube proximate an optical light film in a neat,efficient manner. This method is particularly useful with extractorswhich reflect incident light at a variety of different angles. Forexample, a product marketed under the name SCOTCHCAL™ sold by the 3MCompany of St. Paul, Minn. is one such extractor. Typically suchextractors are installed using a coating of water to facilitate thepositioning of the extractor on the surface to which the extractor willbe attached. Those skilled in the art will appreciate that wetting anoptical light film can be detrimental to the internal-reflectanceproperties of the film and should, whenever possible, be avoided. Thismethod of the present invention therefore comprises first connecting theextractor to a thin film and then disposing the extractor/thin filmlaminate onto the configured sheet of optical light film. Those skilledin the art will appreciate that the present method avoids the need forworking with water in the presence of the optical light film and theinherent risks of wetting the grooves of the optical light film.

One embodiment of the present invention is directed to a light carriercomprising at least one sheet of optical light film 510 which ismaintained in a tube configuration by a novel joint. The optical lightfilm preferably has enough flexibility and sufficient width so that onelongitudinal edge 511 can be moved to a position proximate the otherlongitudinal edge 512 thereby forming a tube, preferably having agenerally cylindrical shape.

The manner of forming one light tube of the present invention is bestillustrated with reference to FIGS. 30 and 31 wherein an optical lightfilm 510 is protected by an outer protective sheet 520 with a use offirst connector 530 and a second connector 540. In the mannerillustrated in FIG. 30, the first connector 530 is most preferablydisposed slightly remote from longitudinal edge portion 511 and is alsopreferably connected to the outer protective sheet 520 at a contactregion slightly remote from a first longitudinal edge 521. In thismanner, a slot is defined by the outer surface of edge region 511 ofoptical light film 510, the connector 530 and the inner side of edgeregion 521 of protective sheet 520. Therefore, when optical light film510 is configured into a tube and the second longitudinal edge region512 is brought around proximate longitudinal edge 511, the secondlongitudinal edge region 512 can be readily inserted into the slot. Inorder to maintain the opposing edges of the outer protective sheet 520in position, a second connector 540 is preferably positioned between theouter surface of protective sheet 520 proximate first longitudinal edge521 and the inner surface of protective sheet 520 proximate the secondlongitudinal edge 522. As shown in FIG. 30, the second connector 540 canreadily be positioned prior to configuring the sheets into a tube. Sincesome adhesive tapes which may be used as connectors with the variousembodiments of the present invention are provided with liners whichprotect the adhesive surface before use, one side of such tapes can beadhered to an optical light film or a protective sheet while leaving theother side of the adhesive tape covered by the protective liner. Thatliner could then be subsequently removed at a different location priorto final assembly. While one preferred embodiment of this inventionaligns the second connector 540 with the opposing edges of protectivesheet 520, such alignment is not necessary in order to obtain thebenefits of the present invention.

The connectors used to join the sheets of the present inventionpreferably comprise strips of tape, most preferably a two-sided adhesivetape or a tape exhibiting adhesive properties throughout such that bothsides and the edges of the tape are sufficiently sticky. One such tapeis a Very High Bond Tape available from the 3M Corporation of St. Paul,Minn. which exhibits adhesiveness throughout. Particularly a clear VeryHigh Bond Tape designated "4910" is particularly useful for bonding thesmooth surfaces of the outer protective sheet 520, while a white VeryHigh Bond Tape having the designation "4952" is particularly useful forconnecting the outer, ridged surface of the optical light film toanother surface. It has been found that the clear tape has a tendency towithdraw from the grooves on the outer surfaces of an optical light filmresulting in a reduction in adhesion. Those skilled in the art will alsoappreciate that the thickness and/or width of the adhesive tape utilizedcan be varied for different applications depending upon such factors asthe strength required and any thickness characteristics inherent in theparticular tube design.

The various embodiments of the present invention can readily bepartially or totally assembled at or close to the site of their ultimateuse. Assembly at such locations greatly reduces the cost of shippingsince the sheets can be shipped in a flat configuration requiring muchless volume than assembled tubes. These and other advantages of thepresent invention will be apparent to those skilled in the art.

An alternative embodiment of the present invention is illustrated inFIGS. 32 and 33. In this embodiment, at least one optical light film 610is substantially sandwiched between an outer protective sheet 620 and aseparate inner protective sheet 650. Those skilled in the art willappreciate that inner protective sheet 650 is most preferably clear. Thetwo protective sheets are configured and connected in the same fashionas the optical light film and outer protective sheet illustrated inFIGS. 30 and 31. A first connector 630 is utilized to connect an outersurface remote from a first edge of region 651 of inner sheet 650 withan inner surface of outer sheet 620 in a manner that forms a slot whichreceives a second edge portion 652 of inner sheet 650. The second edge622 of outer sheet 620 is then configured substantially around the innerprotective sheet 650 using a second connector 640 while at least onesheet of optical light film 610 is substantially sandwiched betweenouter sheet 620 and inner sheet 650. Since the protective sheets are notbeing connected to an optical light film, it is desirable to use a clearVery High Bond Tape such as the "4910" tape referenced above.

This embodiment of the present invention offers several significantadvantages. Primarily, a plurality of optical light films can be readilypositioned at discrete locations in the tube leaving sections of thetube without optical light film. Those skilled in the art willappreciate that controlled amounts of light and various patterns can beprovided by leaving gaps between discrete sheets of optical light filmor by providing light films having extractors or holes which permit the"escape" of light from the light tube.

Illumination devices of the present invention can also be connected attheir terminal ends in order to increase the effective length of thedevice. One aspect of the present invention, illustrated in FIGS. 34 and35, comprises arranging adjacent sections of a multi-section tube in anoverlapping manner. Unlike the other cross-sectional views describedabove, each of these views illustrates portions of two separate tubesegments which are joined at their terminal ends. In this illustratedembodiment, a first segment comprises a terminal edge of a first sheetof optical light film 950 which extends beyond the edges of two othersheets 951 and 952 of the first segment. In a second segment, theoptical light film 960 does not extend to the ends of other sheets 961and 962. As shown in FIG. 35, when the two segments are joined, theouter two sheets 961 and 962 of the second segment will overlap theoptical light film 950 of the first segment. This overlap of sheets fromadjacent segments will strengthen the connection between the segments.As shown in FIG. 35, an additional connector 970 such as a single-sidedtape may be used to hold the segments together.

Another aspect of the present invention comprises a method of disposingan extractor in a light tube proximate an optical light film in a neat,efficient manner. This method is particularly useful with extractorswhich reflect incident light at a variety of different angles. Forexample, a product marketed under the name SCOTCHCAL™ sold by the 3MCompany of St. Paul, Minn. is one such extractor. Typically suchextractors are installed using a coating of water to facilitate thepositioning of the extractor on the surface to which the extractor willbe attached. Those skilled in the art will appreciate that wetting anoptical light film can be detrimental to the internal-reflectanceproperties of the film and should, whenever possible, be avoided. Thismethod of the present invention therefore comprises first connecting theextractor to a thin film, such as G. E. Lexan® suede film and thendisposing the extractor/thin film laminate onto the configured sheet ofoptical light film. A suede film advantageously increases the lightscattering effect of the extractor. Those skilled in the art willappreciate that the present method avoids the need for working withwater in the presence of the optical light film and the inherent risksof wetting the grooves of the optical light film.

Another embodiment of the present invention is directed to a lightcarrier comprising an optical light film disposed within twosubstantially transparent sheets. As illustrated in FIGS. 38 and 39, anoptical light film 1010 comprises a first edge region 1011 and a secondedge region 1012. According to this illustrated embodiment, a connector1030 is advantageously positioned remote from edge 1011 of optical lightfilm 1010 and contacts a transparent middle sheet 1020 at a positionremote from a first longitudinal edge 1021 of the middle sheet 1020. Inthis manner, connector 1030 thereby forms a slot into which the oppositeedge portion 1012 of optical light film and/or longitudinal edge region1022 of middle sheet 1020 may be inserted when the films are formed intoa generally tube configuration, as illustrated in part in FIG. 39. Anouter sheet 1030 comprises a first edge region 1031 and a second edgeregion 1032. According to this preferred embodiment of the presentinvention, the opposing longitudinal edge regions of the outer sheet1030 are positioned in abutting relation when the light carrier isformed. In order to effect this desired configuration, a secondconnector 1040 is positioned on the outer surface of middle sheet 1020at a position remote from first longitudinal edge 1021 and in alignmentwith edge region 1031 of outer sheet 1030. In this manner, the edges ofconnector 1040 and first edge region 1031 are most preferably aligned. Athird connector 1050 is advantageously disposed on the inner surface ofthe second edge region 1032 of outer sheet 1030 such that when the outersheet 1030 is formed into a generally tubular configuration, the thirdconnector 1050 connects the second edge region 1032 of outer sheet 1030with the outer surface of first edge portion 1021 of middle sheet 1020.As shown in FIG. 39, the edges of outer sheet 1030 are advantageously,but not necessarily, disposed in abutting relation in order to provide alight carrier having a smooth outer surface.

While different types of connectors may be utilized without departingfrom the scope of this embodiment of the present invention, onepreferable material for first connector 1030 comprises a double-sided,opaque tape specifically designed to hold the outer grooves of opticallight film 1010 securely for extended periods of time. Connectors 1040and 1050 may comprise substantially transparent double-sided tapes. Forexample, the adhesive tape can be a Very High Bond Tape available fromthe 3M Corporation of St. Paul, Minn. which exhibits adhesivenessthroughout. Those skilled in the art will also appreciate that thethickness of the adhesive tape utilized can be varied for differentapplications depending upon such factors as the strength required andany thickness characteristics inherent in the particular tube design.

According to one preferred embodiment of the present invention, themiddle film comprises Lexan® available from G. E. Plastics, Inc., U.S.A.having a matte/velvet finish, e.g. Model 8B35, which is a diffusingfilm. The outer sheet preferably comprises Lexan® and most preferablycomprises enhanced ultraviolet stability for outdoor use. For example,Lexan® Model HP92W, also available from G.E. Plastics, U.S.A., offersdesirable ultraviolet stability and abrasion resistance.

From the present description, it will be appreciated that rings, such asthe heat resistant retaining rings described above, will have many usesin illumination devices. Rings constructed in the fashion illustrated inFIGS. 36 and 37 may also be utilized with other illumination devices.

FIG. 36 illustrates a silicon ring of the present invention comprising asingle axial slot and a radial slot. The axial slot is defined by aninner wall 810 and an outer wall 820 which extend from a body portion830. An axial groove 840 faces inwardly in this illustrated embodiment.Inwardly facing radial groove 840 may be utilized to support a lens, apiece of tempered glass, a mirror, or some other desired element. Thering illustrated in FIG. 36 the axial groove can be utilized to receivea portion of a lamp housing or a light tube. Additionally, from thepresent description, those skilled in the art will appreciate that otherconnecting members can be connected to the illustrated ring, forexample, to body portion 830 in order to connect other desired elements.For example, the rim of a light tube could be positioned within theaxial slot while a lamp housing could be connected to body portion 830.As illustrated in FIG. 37, one embodiment of the present inventioncomprises a double axial slot configuration wherein the retaining ringcomprises an upper axial slot 705 and a lower axial slot 706. The upperaxial slot 705 being defined by inner wall 720 and outer wall 730 andthe lower axial slot 706 being defined by outer wall 740 and inner wall750. In this particular embodiment, upper slot 705 receives opticallight film 710 and lower slot 706 receives bulb housing 700. Flange 760projects from inner wall 750 and into lower slot 706 and acts as aretaining means for bulb housing 700. Bulb housing 700 comprises arecess 715 for receiving flange 760 to retain bulb housing 700 inposition. From the present description, those skilled in the art willappreciate that the ring shown in FIGS. 36 and 37 have broadapplications with illumination devices. While the upper and lower axialslots above have been generally described as being vertically oriented,it is conceivable that the slots could be disposed in a more horizontalfashion or at virtually any angle.

I claim:
 1. A light carrier comprising:a sheet of optical light filmcomprising a first longitudinal edge portion and a second longitudinaledge portion, said optical light film having sufficient flexibility toallow said first longitudinal edge portion to be disposed in a positionproximate said second longitudinal edge portion; a second sheetcomprising a first longitudinal edge, a second longitudinal edge, and afirst contact region remote from said first longitudinal edge; and meansfor maintaining said optical light film in a tube configurationcomprising a first connector having at least one adhesive portion, saidfirst connector connected to said optical light film at a first distancefrom said first longitudinal edge portion and to said second sheet at asecond distance from said first longitudinal edge; and wherein saidfirst distance is less than said second distance.
 2. A light carriercomprising:an optical light film formed into a light tube; a substrate;and an extractor laminated to said substrate wherein saidsubstrate-extractor laminate is disposed within said tube.
 3. A lightcarrier according to claim 2 wherein said substrate provides lightscattering properties.